短語(yǔ)詞組短語(yǔ)visitor design pattern 訪(fǎng)問(wèn)者設(shè)計(jì)模式The Visitor Pattern 訪(fǎng)問(wèn)模式Visitor Pattern Identifying 訪(fǎng)問(wèn)者模式識(shí)別 返回 visitor pattern